Magnetic reversing switch



Sept. 19, 1944.

W. C. FURNAS ETAL MAGNETIC REVERSING SWITCH Filed Ma 21, 1941 3Sheets-Sheet (m ll! Patented Sept. 19, 1944 UNITED STATES PATENT OFFICEMAGNETIC REVERSING SWITCH William C. Furnas and Daniel G. Spotts,Batavia 111.; said Spotts assignor to said William C. Furnas, doingbusiness as Furnas Electric Company, Batavia, Ill.

4 Claims.

The present invention relates generally to improvements in electricswitch assemblages, and relates more specifically to variousimprovements in the construction and operation of magnetically operablereversing switch mechanisms.

An object of this invention is to provide an improved magnetic reversingswitch which is simple, compact and durable in construction, and whichis also highly efiicient in operation.

It has heretofore been common practice to operate various types ofswitches magnetically, and when magnetic operation is utilized to effectactuation of a reversing switch for motors or the like, it is necessaryto provide some form of automatic interlock between the forward andreverse switch elements, in order to positively prevent both sets ofcontacts from closing simultaneously, since such action would produceshort circuiting of the power line. In the prior commercial magneticreversing switch assemblages, it has been customary to provide twoseparate and independent sets of contacts, one for forward and the otherfor reverse operation, connected in parallel; and when these assemblagesare utilized in multi-phase systems, the three leads both of the mainline and of the motor, are connected to both sets of contacts, and themovable contacts of both sets are mechanically interlocked so as toavoid short circuits. The mechanical interlock between the two sets ofswitch contacts of these prior multi-phase magnetic switch mechanisms,is ordinarily interposed between the movable cores of the two magnetassemblages, and the prior switches of this general type are thereforerelatively cumbersome, complicated, costly, and insufficiently durableto withstand rapid and repeated operation for any great length of time.

It is therefore a more specific object of our present invention, toprovide a new and useful poly-phase magnetic reversing switchassemblage, all of the elements of which are embodied in a singlerelatively simple and compact unit.

Another specific object of the present invention is to provide animproved magnetically operated reversing switch wherein the number ofcontacts and the number of terminal connec tions are reduced to aminimum, and in which the several contacts and terminals are effectivelysegregated and insulated from each other.

A further specific object of the invention is to provide an improvedmagnetic switch unit; in which the movable elements are of relativelylight but durable construction, thereby enhancing the speed of action byminimizing the effects of inertia, and also prolonging the life of theswitch to a maximum.

Still another specific object of our invention is to provide an improvedreversing switch assemblage, the various parts of which may beconveniently manufactured and assembled, and which may be produced atmoderate cost.

An additional specific object of this invention is to provide animproved multi-phase magnetic reversing switch in which the structure issimplified by making the mechanical interlock an inherent part of theswitch assemblage, thus eliminating elements such as pull-rods, levers,and the like.

Another specific object of the invention is to provide a reversingswitch mechanism wherein friction and resultant wear are reduced to aminimum, thus producing a durable and compact assembly having maximumcapacity and which is operable at high speed.

A further specific object of the present invention is to provide amagnetic reversing switch unit wherein the actuating magnets are closelyassociated with the contacts, in alinement with each other, and in whichall elements are effectively protected.

Still another object of our invention is to provide various otherimprovements in the details of construction and operation of poly-phasemagnetic reversing switches, whereby the cost of construction is reducedto a minimum and the efiiciency is enhanced to a maximum.

These and other objects and advantages will be apparent from thefollowing description.

A clear conception of the several features constituting our presentinvention, and of the mode of constructing and of operating magneticreversing switches built in accordance with the improvement, may be hadby referring to the drawings accompanying and forming a part of thisspecification wherein like reference characters designate the same orsimilar parts in the various views.

Fig. 1 is a part sectional left side elevation of one of the improvedmagnetic reversing switch units;

Fig. 2 is a front view of the improved reversing switch mechanism ofFig. 1 removed from its housing;

Fig. 3 is a right side elevation of the switch mechanism with thehousing omitted;

Fig. 4 is a top View of the switch contact assemblage, showing thecontact actuating bars in section;

Fig. is a winding diagram showing the improved magnetic reversing switchapplied in a .iree-phase motor circuit;

Fig. 6 is a vertical section through the switch contact assembly, takenalong the line 6.6 of Fig. 1 and showing the reverse interlock contactsclosed;

Fig. '7 is a similar section through the contact assemblage, taken alongthe line 1-1 of Fig. 1, and showing the switch in reverse;

Fig. 8 is another similar section through the contact group similarlypositioned in reverse, and taken along the line 8-8 of Fig 1;

Fig. 9 is still another similar section with the elements in reverse,taken along the line 99 of Fig. 1; and

Fig. 10 is a transverse horizontal section through the lower magnetassemblage, taken along the line Iii-l9 of Fig. 3.

While our invention has been shown' and described herein as having beenspecifically embodied in a unitary vertically disposed thereephasemagnetic reversing switch assemblage of a specific type, it is not theintent to thereby unnecessarily restrict the scope or utility of theseveral features constituting the improvement.

Referring to the drawings, the improved polyphase magnetic reversingswitch unit shown therein by way of illustration, comprises in general,an upright main support or base plate I2; a multiple switch assembly Afirmly mounted upon the medial portion of th base plate I2 and havingcentral sets of fixed contacts l4, l5, l6 interchangeably cooperablewith upper sets of movable forward contacts ll, l8, l9, and with lowersets of movable reverse contacts 20, 2 l, 22; an upper magnet assemblageB associated with the base plate 12 above the switch assembly A andhaving a vertically slidable member 23 connected with the upper movablecontacts 11, I8, I 9 by means of insulating bars 24; a lower magnetassemblage C associated with the base plate l2- below the switchassembly A and also having a vertically slidable member 25 likewiseconnected with the lower movable contacts 20, 2 I, 22

- by means of other insulating bars 26; interlock mechanism D alsoconstituting a part of' the switch assembly A; and a housing comprisinga supporting frame 2! secured to the base plate l2, and a removablecover 28, coacting with the frame to enclose and protect the switch andmagnet assemblages.

The compact central switch assembly A consists primarily of a centralhorizontal auxiliary supporting element or plate 29 upon which the fixedsets of contacts [4, l5, l6 are fixedly mounted, upper and lowerhorizontal elements or plates 39, 3| respectively spaced from thecentral plate 29 and being rigidly secured to the support or base platel2, and a vertical front plate 32 which may be formed integral with theplate 29 and interconnects the plates 29, 39, 3|. The blocks or plates29, 30, 3!, 32 are all formed of insulating material, and the medialplate 29 is provided with vertical fins or walls I 3 which abut againstthe upper and lower plates 30,v 3i and segregate the contacts I4, [5, 16from each other. The upper plate provides a reaction block for a pair ofcompression springs 33 which coact with the upper armature 23'but thelower plate 3! does not coact with such springs when the unit isdiscontacts are normally urged toward the adjacent fixed contacts bymeans of other compression springs 34 embracing the adjacent contactcarrier bars 24, 26, see Figs. 7 and 8.

The upper and lower magnet assemblages B, C are spaced apart and are ofsimilar construction but are reversely positioned in vertical alinementwith each other, and each magnet assembly comprises a laminatedE.-shaped magnetic core 35 fixedly secured to the support or base plateI2 by means of brackets 36; a magnet winding or coil 31 cooperating withthe core 35 to magnetize the same when the coil is energized; and alaminated armature or cross-bar 38 carried by and being movable witheach of the movable members 23, 25, and cooperating with the adjacentmagnet core 35, see Figs. 1 and 10. The yok shaped members 23, 25, arepreferably formed of relatively thin and light but durable non-magneticmetal; and these yoke members 23, 25 are slidably confined upon thefixed brackets 36. The movable contact carrier bars 24, 26 which areformed of insulating material, are detachably attached to the members23, 25 respectively, as clearly shown in Fig. 1, and are slidablyconfined within the contact assembly plates 30, 3|, see Fig. 4.

The improved interlock mechanism D comprises upper and lower sets oftransverse movable contacts 39, 49'respectively carried by the adjacentactuating bars 24, 26, and being interchangeably cooperable respectivelywith sets of fixed contacts 4|, 42 secured to the central contact as- Vsembly plate 29, see Fig. 6. The contact carrier posed vertical, seeFigs. 1, 3 and 7-. The movable 75 bars 24, 26 which carry the movableinterlock contacts have adjacent end portions 43, 44 respectively, whichare slidable in slots in the medial plate 29, and are of such lengththat they 7 will positively prevent simultaneous closing of both theupper and lower sets of movable contacts, as clearly illustrated inFigs. 6 and 9. The upper set of fixed interlock contacts M is connectedin series with the upper magnet coil, while the lower set of fixedinterlock contacts 42 is likewise connected in series with the lowermag- 26 will prevent simultaneous 'closing'of the upper and lowercontacts and will therefore positively prevent short circuiting. Thecontacts l6 are also permanently connected to the interlock contacts 42by a conductor 46, see Figs. 3, 4 and 6.

The improved reversing switch is' operable with the aid of a push buttoncontrol to efiect either forward or reverse operation, or stoppage, ofan electric motor M or other reversely operable electric device, asshown in the diagram of Fig. 5. The push button control has a forwardbutton switch 41, a reverse button switch 48, and a stop button switch49; and when the switch 41 is closed, the magnet assembly B will beeffective,

, whereas when the switch- 48 is closed, the'magnet assembly C'will beactive, as shown in Figs. 6 to 9 inclusive. When the stop button 49ispressed, either magnet assembly B or C, whichever is energized, willbev de-energized, and'the reversing switchmechanism will assume inactivepositionwith all contacts open as shown in Figs. 1, 3 and The main lineE may be introduced into the reversing switch housing through openingsin the lower wall of the frame 21, and should have one lead 50 connectedto one of the fixed contacts I6, another lead 5I connected to one of thefixed contacts I4, and the third lead 52 connected to one of theremaining fixed contacts I5, as shown in the diagram so that when eithermagnet assembly B, C is active, the corresponding movable contacts willengage the fixed contacts, and th corresponding interlock will becomeeffective and remain so until positively broken either by reversing theoperation'or by actuatin the stop switch.

During normal use of the improved polyphase reversing switch, when thesystem is in the condition shown in the diagram of Fig. 5, with the stopbutton switch 49 closed, all other contacts will be open, both magnetassemblages B, C will be de-energized, and the motor M will be idle.

If the reverse push button switch 48 is then closed, the lower magnetassembly C will be energized and the lower member 25 will be elevated toquickly close the lower interlock contacts 40, 42, and to simultaneouslybring the lower movable contacts 20 into engagement with the two fixedcontacts I4, and the lower movable contacts 2I, 22 into engagement withone of each of the fixed contacts I5, I6. The motor M will then beconnected to the main line E for reverse operation, and will remain thuconnected until the stop push button switch 49 is opened, whereupon themagnet assembly C will be de-energized and the lower member 25 togetherwith the lower bars 38, 2B and movable contacts 20, 2I, 22, 40 will dropby gravity, thus breaking the interlock and line circuits and restoringthe switch elements to inactive position.

If, on the other hand, the forward push button switch 41 is closed afterthe stop switch 49 has been closed, the upper magnet assembly B will bebe energized and the upper member 23 will be moved downwardly to quicklyclose the upper interlock contacts 39, 41, and to simultaneously bringthe upper movable contacts I'I into engagement with the two fixedcontacts I4, the upper movable contacts I8 into engagement with bothfixed contacts I5, and the upper movable contacts I9 into engagementwith the two fixed contacts I6. The motor M will then be connected tothe main line E for forward operation, and will remain in this conditionuntil the stop push button switch 49 is again opened, whereupon themagnet assembly B will be de-energized and the upper member 23 togetherwith the upper bars 38, 24 and movable contacts I'I, I8, I9, 39 will beelevated by the springs 33, thus breaking the interlock and linecircuits and again restoring the switch elements to inactive position.

From the foregoing detailed description of the construction andoperation of the improved magnetic reversing switch, it-will be apparentthat the relatively simple and compact switch assembly operates quicklyand positively for both forward and reverse operation, and can bereadily restored to neutral or inactive position with the aid of thestop button switch 49. While the magnet assemblage B, C are locatedclosely adjacent to the central switch and inkerlock assemblage A, D,the various contacts are thoroughly insulated from the magnets and fromeach other, wherever necessary, by the insulated motion transmissionbars 24, 26 and by the insulation plates 29, 30, 3|, 32. The use of theinsulated bars 24, 26 i therefore important, and the formation of thesliding armatures 23, 25 of light non-magnetic sheet metal is alsoimportant in order to enhance the speed of operation and to eliminatedelay due to inertia. While the lower movable contacts are returned toopen position by gravity and the upper movable contacts are thusreturned by the springs 33, this mode of returning the movable contactsis primarily applicable to vertically arranged switches; and if theimproved switch assembly is to be used in horizontal position, thensprings 33 should also be provided between the fixed plate 3| and themovable member 25. The springs 34 which embrace the bars 24, 26 andcoact with the adjacent movable contacts, serve only to insure properseating of all of these contacts, and the projections 43, 44 at theadjacent ends of the bars 24, 26 are extremely important since theypositively prevent possibility of short circuiting by preventingsimultaneous closing of both forward and reverse contacts. The improvedcontact supporting and housing assembly comprising the insulating plates29, 30, 3 I, 32, may be readily constructed, assembled and dismantled,and provides a compact and highly effective switch assembly A, and theadditional housing afforded by the frame 21 and cover 28 also protectsthe switch mechanism and provides a neat and attractive unit, whilepermitting convenient access to the normally concealed parts. Theimproved magnetic switch assemblage may obviously be manufactured andsold at moderate cost since the meta1 parts are formed primarily ofsheet metal stampings, and. has proven highly practical and efiicient inactual use.

It should be understood that it is not desired to limit this inventionto the exact details of construction or to the precise mode of use,herein shown and described, for various modifications within the scopeof the claims may occur to persons skilled in the art.

We claim:

1. In combination, an elongated rigid support, a pair of independentelectro-magnets having spaced-apart oppositely facing E-shaped magnetcores fixedly mounted upon said support and each core having anenergizing coil mounted therein, a group of stationary forward andreverse and interlock contacts mounted upon said support between saidelectro-magnets, a rectilinearly movable set of forward and interlockcontacts disposed between one of said electromagnets and said group offixed contacts, another rectilinearly movable set of reverse andinterlock contacts disposed between the other of said electro-magnetsand said fixed contacts, the interlock contacts of both of said movablesets being directly cooperable to positively prevent simultaneousclosing of said forward and reverse movable contacts, a magneticarmature bar spanning the open side of each of said E-shaped coresremote from said contacts, and a light non-magnetic one-piece U-shapedyoke connecting each of said armature bars with the nearest set of saidmovable contacts, each of said yokes having side arms slidably coactingwith the adjacent magnet core and also having an integral transverseportion of approximately the same thickness as the side arms connectedto the adjacent set of movable contacts.

2. In combination, an elongated rigid support, a pair of independentelectro-magnets having spaced-apart oppositely facing E-shaped magnetcores fixedly mounted upon said support and each core having anenergizing coil mounted therein, a group of stationary forward andreverse and interlock contacts mounted upon said support between saidelectro-ma-gnets, a rectilinearly movable set of forward and interlockcontacts disposed between one of said electromagnets and said group offixed contacts, another rectilinearly movable set of reverse andinterlock contacts disposed between the other of said electro-magnets.and said, fixed contacts, the interlock contacts of both of said movablesets being directly cooperable to positively prevent simultaneousclosing of said forward and reverse movable contacts, a magneticarmaturebar spanning the open side of each of said E-shaped cores remotefrom said contacts, and a light non-magnetic one-piece U-shaped yokeconnecting each of said armature bars with the nearest set of saidmovable contacts, each of said yokes having side arms slidably coactingwith the adjacent magnet core and also having an integral transverseportion of approximately the same thickness as the side arms connectedto the adjacent set of movable contacts, and each of said movablecontacts having a supporting bar slidably mounted upon said rigidsupport and detachably attached to the transverse portion of theadjacent yoke.

3. In combination, an elongated rigid support, a pair of independentelectro-magnets having spaced-apart oppositely facing E-shaped magnetcores fixedly mounted upon said support and each core having anenergizing coil mounted therein, a group of stationary forward andreverse and interlock contacts mounted upon said support between saidelectro-magnets, a rectilinearly movable set of forward and interlockcontacts disposed between one of said electromagnets and said group offixed contacts, another rectilinearly movable set of reverse andinterlock contacts disposed :between the other of said electro-magnetsand said fixed contacts, the interlock contacts of both of said movablesets having alined projections rectilinearly slidable with respect tosaid support and directly cooperable with each other to positivelyprevent simultaneous closing of said forward and reverse movablecontacts, a magnetic armature bar spanning the open side of each of saidE-shaped cores remote from said contacts, and arlight non-magneticone-piece U-shaped yoke connecting each of said armature bars with thenearest set of said movablecontacts, each of said yokes having side armsslidably coacting with the adjacent magnet core and also having anintegral transverse portion of approximately the same thickness as theside arms connected to the adjacent set of movable contacts.

4. In combination, an elongated rigid support, a pair of independentelectro-magnets having spaced-apart oppositely facing E-shaped magnetcores fixedly mounted upon said support and each core having anenergizing coil mounted therein, a group of stationary forward and re-.verse and interlock contacts mounted upon said support between saidelectro-magnets, a rectilinearly movable set of forward and interlockcontacts disposed between one of said electromagnets and said group offixed contacts, another rectilinearly movable set of reverse andinterlock contacts disposed between the other of said electro-magnetsand said fixed contacts, the interlock contacts of both of said movablesets having alined projections rectilinearly slidable with respect tosaid support and directly cooperable with each other to positivelyprevent simultaneous closing of said forward and reverse movablecontacts, a magnetic armature bar spanning the open side of each of saidE-shaped cores remote from said contacts, and a light non-magneticone-piece U-shaped yoke connecting each of said armature bars. with thenearest set of said movable contacts, each of said yokes having sidearms slidably coacting with the adjacent magnet core and also having anintegral transverse portion of approximately the same thickness as theside arms connected to the adjacent set of movable contacts, and each ofsaid movable contacts having a supporting bar slidably mounted upon saidrigid support and detachably attached to the transverse portion of theadjacent yoke.

WILLIAM C. FURNAS. DANIEL G. SPO'I'IS.

